Virgin broadband sluggish again

Yet again it seems that Virgin Media have signed up more customers than the infrastructure can support. They are upgrading it (say tech support) but if you find as I do that it slows down in the evening from the promised 50Mb to 5Mb or even, a couple of nights, less than 1MB then give tech support a call and demand a refund. Apparently the problem (not listed as such on the service status, but acknowledged when you press them) should be fixed by 23 Dec.